Global Dimming

Global Dimming

Friday, September 20, 2013

The global dimming is a gradual reduction in the measured intensity of the sunlight that reaches the earth's surface. Since the 1950s, were installed to Antarctica hundreds of stations from the Arctic to measure the sunlight. Mid-1980s, Dr. Ohmura Atsumu employed (Swiss Federal Institute of Technology Zurich) with the analysis of the data.His remarks on the "Global Dimming" were included only hesitantly in the professional world. The global dimming effect has been well documented by Gerald Stanhill, an English researcher, in Israel. He compared radiance measurements from 1950 to the 1980s. It was discovered by measuring the potential evaporation by means of evaporation meter (class A pan) that the annual amount of evaporation of the water has decreased worldwide.

Another series of measurements in the Indian Ocean in 1999 showed that the air pollution in the global blackout seems to play a major role. There reasonably scientists in areas with high air pollution is lower by 10% sunlight than in areas with clean air.

From 1961 to 1990, the solar radiation at the earth's surface has decreased by an estimated 4%. This value is subject to significant regional differences. Thus, the highest darkening over the area of ​​the United States was to be measured at 10%.

Currently, it is thought that this effect is due to the increased concentration of aerosols in the atmosphere. These result from the combustion of organic matter (wood, coal, oil, gas). Accordingly, the major hotspots major industrial nations in Asia, North America and Europe would be. But burning oil wells in Kuwait or slash and burn the rain forest in Brazil are mentioned as possible causes.

The emitted aerosols reflect both the sunlight, on the other condenses on them - just as in natural particles (such as dust or ice) - the water and clouds are formed. The high number of anthropogenic aerosols are more droplets are smaller but the same form.Thus, these clouds are longer due to the higher albedo and reflect sunlight into space even more. Less sunlight means to a cooling of the atmosphere, on the other, less evaporation on the ground and thus less precipitation. The soil is moist, there are more clouds, but it rains less.

Global dimming acts opposite to the global warming. During the global blackout by reflection of the sun's rays to cool the climate, heat greenhouse gases such as water vapor, CO2 and CFCs to the atmosphere. With the increasing filtration of exhaust gases in the world is global dimming since the mid-1980s again. Global warming is increasing but due to the increased energy consumption of the people on to - the average global temperature has risen by 0.74 ° C between 1906 and 2005.

It is believed that global dimming has dampened by their cooling effect, the previous extent of the greenhouse effect. If successful measures to combat global dimming are taken - the reduction of particulate emissions through filters, etc. - and thereby cease their cooling effect, this could mean that the previously predicted extent of global warming is surpassed. Expected some climate scientists have been an increase in the average temperature of about 5 ° C by 2100 could result in a reduction of global dimming to increase 8-10 ° C.

Some climate scientists have hypothesized that the problems caused by aircraft contrails contribute to global dimming afford the constant air traffic but never left a review of the hypothesis. After the terrorist attacks of 11 September 2001, was for three days a ban on the entire United States. During this time, it was observed that the temperature difference between day and night across the United States by 1.1 ° C was higher than the day before or after the flight ban. Such a high temperature difference was not measured there in the past thirty years.

According to the German Aerospace Center DLR carry on average the contrails of aviation with 0.1% of the global cloud cover at.

Source: www.wikipedia.de